1. Field of the Invention
This invention relates to compositions of matter and methods of producing the same and is particularly directed to improved solid propellant NF.sub.3 --F.sub.2 gas generators derived from self-clinkering NF.sub.4.sup.+ salts, together with methods for producing such gas generators.
2. Description of the Prior Art
NF.sub.4.sup.+ salts are the key ingredients for solid propellant NF.sub.3 --F.sub.2 gas generators, as shown by D. Pilipovich in U.S. Pat. No. 3,963,542. These propellants consist of a highly over-oxidized grain using NF.sub.4.sup.+ salts as the oxidizer. Burning these propellants with a small amount of fuel, such as aluminum powder, generates sufficient heat to thermally dissociate the bulk of the oxidizer. This is shown for NF.sub.4 BF.sub.4 in the following equation: EQU NF.sub.4 BF.sub.4 .fwdarw.NF.sub.3 +F.sub.2 +BF.sub.3
as can be seen from the equation the gaseous combustion products contain the volatile Lewis acid BF.sub.3. This disadvantage of a volatile Lewis acid byproduct is shared by all the previously known NF.sub.4.sup.+ compositions. These volatile Lewis acids possess a relatively high molecular weight and a low .gamma. value (.gamma.=C.sub.pi /C.sub.vi), relative to the preferred diluent helium and frequently act as a deactivator for the chemical HF-DF laser. Consequently, these volatile Lewis acids must be removed from the generated gas prior to its use in an efficient chemical laser. Based on the state of the art, heretofore, this would be achieved by adding a clinker forming agent, such as KF, to the solid propellant formulation. The function of this additive served to convert the volatile Lewis acid, such as BF.sub.3, to a non-volatile salt as shown by the following equation: EQU KF+BF.sub.3 .fwdarw.KBF.sub.4
The principal disadvantages of this approach are that, even if an excess of KF is used, complete clinkering cannot always be guaranteed, and that the addition of the KF severely degrades the yield of NF.sub.3 --F.sub.2 obtainable per pound of formulation. This problem could be solved by using NF.sub.4.sup.+ containing compositions derived from non-volatile Lewis acids. However, the synthesis of such compositions has previously been unknown, since highly stable and non-volatile Lewis acids are polymeric and contain coordination-wise saturated central atoms. Consequently, these compounds possess very little or no acidity, which renders the synthesis of such salts very difficult.